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<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    let arr = [1,2,3,4,5,6];

    // let value = 1;
    // arr.forEach(item => {
    //   value = item * value
    // })
    // console.log(value);

    //(prev, current) => prev * current 『reducer 函数』
    let value2 = arr.reduce((prev, current) => prev * current); //reduce 减少
    console.log(value2);

  </script>
</body>
</html>